Working a youngster into contact?

I now feel Alli is at a stage in her training where she should be starting to come into a contact and working over her back properly. She is six, but only backed in last summer. 7 in April.

She can work beautifully on the lunge without side reins but its a bit hit and miss as to whether she does. I have started using side reins on the lunge but she always works above the bit Tried doing loads of transitions to get her lifting her forehand and stepping under with her back legs, kind of worked but she wasn't working as well as I'd like her to.

What kind of lunge exercises help youngsters work into a contact?

While being ridden she is a dream on hack, but is tense and piggy in our 'arena' in trot- trying to canter or jog. This is getting much better but repetative schooling makes her go backwards. I have been spiraling her in and out in all walk and trot and she sometimes steps under *lots of praise* but mostly falls in/out and pushes through my supporting leg. She also gets bored of spiraling Tried doing leg yields which she understands on the ground but not in the saddle. Again, we are getting there, slowly.

What can I do to mix up her schooling but help her come into a rounded contact?

She has fairly good strength across her back now from lots of hacking, but I know she needs to build more strength up in order to lift her back to work rounded whilst carrying a rider for any length of time. It is difficult to do pole work due to soggy fields at the moment, but she is very confident over trot poles and I have done lots of this when able to.

So yeah, any suggestions for getting a youngster to work in a soft, rounded contact? Willing to give anything a try really, to keep things spiced up!